The present invention relates to a let-off warp beam coupling device used when a let-off warp beam is coupled to or uncoupled from a weaving machine for coupling and uncoupling an end of a rotating shaft of the let-off warp beam and a beam gear. The beam gear is positioned on the weaving machine side and provided movably in the axial direction of the beam gear.
An example of a conventional let-off warp beam coupling device for coupling and uncoupling a shaft-end of a let-off warp beam and a beam gear on the side of a weaving machine is as shown in FIG. 1. In the device, on a surface around one end of a beam shaft 2 of a let-off warp beam 1, there was formed a spline portion 3, to which a beam gear 4 was fitted in coaxial. The beam gear 4 is provided on the side of the weaving machine for driving the let-off warp beam 1 through the beam shaft 2 and has a fitting bore 5 at the center with grooves 4a formed inside so as to be fitted to the spline portion 3. The beam gear 4 is provided so as to be movable backward and forward with respect to the end of the beam shaft 2 of the let-off warp beam 1 by a back and forth driving mechanism 6. This allows the grooves 4a of the fitting bore 5 of the beam gear 4 to be engaged and disengaged with the spline portion 3.
There was also another type of the let-off warp beam coupling device as shown in FIG. 2. The device is provided with a clutch 8 comprising a channel 6 provided at an end surface of the beam shaft 2 of the let-off warp beam 1 and a protruded strip 7 provided so as to be freely fitted to the channel 6. The protruded strip 7 of the clutch 8 is provided integrally with the beam gear 4 on the side of a weaving machine with its center on the axis of the beam gear 4. It is movable together with the beam gear 4 backward and forward with respect to the beam shaft 2 by the back and forth driving mechanism 6.
In each of the conventional devices, there were problems such as misalignment of the axis of the beam shaft 2 of the let-off warp beam 1 with the axis of the beam gear 4 or the back and forth driving mechanism 6. Backlash produced between the spline portion 3 and the grooves 4a of the fitting bore 5, and rattling produced between the channel 6 and the protruded strip 7 of the clutch 8. In addition, this failed to transmit accurately the rotating motion of a pinion, which is in a driving mechanism for driving the beam gear 4 provided on the weaving machine side, to the let-off warp beam 1. As a result, variation was caused in the tension of the warp fed from the let-off warp beam.
In view of the foregoing, it is an object of the present invention to provide a let-off warp beam coupling device which can accurately transmit a driving motion without any variation factors such as backlash and misalignment.